The present invention is primarily directed to campers' or hunters' compasses and more particularly to an improved compass providing means for enabling a user to readily ascertain a reverse direction of travel back to a point of origin without the need to make mathematical calculations or re-adjustments of the initial compass settings. The primary object of the invention is to avoid disorientation and confusion by hunters and campers in charting a return trip to the point of departure, e,g, a campsite. The invention is also designed for and easy to use, fast and exact for taking backbearings (compass bearings from a visible point at a distance away and towards the user"). Such backbearings are required for several tasks in land navigation.
The present invetion provides an improvement over a known compass sold under the registered trademark SILVA. This known compass, also termed as a protractorcompass, includes three (3) basic elements, namely, a rotatable compass housing, having indicia for orienting North, South, East and West and usually also a circular graduation (0-360); a magnetic compass needle, freely rotating in the housing to align itself with magnetic north; and a baseplate, usually with at least one straight edge parallel to a direction of travel lines(s). In operation of the known compass, the straight edge of the plate is aligned with a desired direction of travel on a map. Thereafter, the compass housing is turned such that the North indicators thereon are in alignment with actual magnetic North as designated on the map. To orient himself to the planned direction of travel, the user then holds the compass in his hand with the direction of travel arrow or line pointing straight ahead of him, and turns his body with the compass until the magnetic needle is rotated into alignment with the magnetic north indicators on the compass housing. Guided by the direction of travel arrow on the plate, which is permanently marked or mounted parallel to the straight edge of the baseplate, the user then proceeds to walk in a straight direction guided by the arrow. By checking now and then that the magnetic needle remains in alignment with the magnetic north setting designated by the compass housing, the user travels in the desired direction until reaching his destination.
It is quite common, that an outdoorsman, especially a hunter, uses his compass to stroll out from camp in a set direction and then wants to turn around and return to his starting point, e.g., is campsite, by backtracking. He may use his compass for this purpose in different ways. He may figure out the backbearing by adding 180 degrees to his compass setting on the way out, if that setting was less than 180 degrees, or by subtracting 180 degrees if the original setting was more than 180 degrees. Then he adjusts the orientation of the compass housing by setting it on this backbearing, and thereafter uses the compass in the normal way. In the alternative, he may use one of the orienting members of the compass in a reverse position, either by holding the compass plate in a reversed position, with the direction of travel arrow pointing towards himself and sighting the opposite direction, or by orienting the magnetic needle in a reversed position with its North end towards the South marking on the housing and then using the direction of travel arrow in the normal way for his return trip.
It is apparent that the "backtracking" procedures described above require either mathematical calculations or adjustments of initially set compass orientations to conform to the planned return trip. These calculations and/or manipulations and/or re-adjustments of the initial settings of the compass may easily result in imprecision, error or confusion in charting a return path, particularly if used by inexperienced outdoorsmen or used during adverse weather or poor visibility conditions, such as those experienced in the dusk of the evening. The result of errors or confusion in charting a return path under such circumstances may result in a hiker becoming disoriented and unable to find his way back to camp or other desired return location. In other words, he would get lost with potential tragic consequences.
The prior art compasses discussed above are described and illustrated in a brochure entitled "READ THIS OR GET LOST" by Silva Compass Co. and in a book entitled "BE EXPERT WITH MAP AND COMPASS" authored by the applicant, Scribner-MacMillan).
It is the primary object of the present invention to provide means on the compass for automatically setting a backbearing indicating the return path or travel back to a campsite or other point of departure, without requiring any adjustment of the initial compass settings, physical re-orientation or manipulation of the compass relative to the user, or any mathematical calculations made by the user. In this manner, the return path to the campsite is charted in a simplified manner which greatly reduces confusion, miscalculation, imprecision or error by the user. The improved compass also has a positive psychological effect, substantially increasing a users' self-reliance on his tracking skills and abilities.